Question: Add.
Explanation: There are many ways to solve this problem. Let's see two ways we can solve it. Place value table Let's line up the numbers by their decimal places. Tens Ones $.$ Tenths Hundredths $1$ ${3}$ $.$ ${5}$ ${3}$ $5$ $.$ ${0}$ ${0}$ Because $5$ is a whole number, we can add a decimal point and two $0$ 's behind to make the columns align. Now, let's add each place value column. Tens Ones $.$ Tenths Hundredths $1$ ${3}$ $.$ ${5}$ $3$ $+$ ${5}$ $.$ ${0}$ $0$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $1$ $8$ $.$ $5$ $3$ Decomposing the numbers We can group the whole numbers together and the decimals together. $\begin{aligned} &({13} + {5}) + {0.53}\\\\ &=18 + {0.53}\\\\ &=18.53 \end{aligned}$ $18.53 = 13.53 + 5$